PROJECT SUMMARY/ABSTRACT: Neuromyelitis optica (NMO) is an autoimmune disease of the CNS characterized by T cell and antibody responses to the water channel protein Aquaporin 4 (AQP4) and myelin oligodendrocyte protein (MOG). NMO patients often suffer from blindness and paralysis as a result of chronic damage to the optic nerves and spinal cord. Current treatments such as high dose corticosteroids, plasmapheresis and rituximab are expensive, non- curative and fail to provide durable disease control. The Miller lab has developed a method using carboxylated biodegradable nanoparticles composed of the FDA-approved biopolymer polylactide-co-glycolide (PLG) to encapsulate proteins or peptides [PLG(Ag)] for induction of T cell tolerance for treatment of autoimmune models of Multiple Sclerosis (EAE) as well as other autoimmune and allergic diseases. Following i.v. infusion, PLG(Ag) NPs are taken up by tolerogenic antigen presenting cells (APCs) in the liver and splenic marginal zone via the MARCO scavenger receptor. These APCs present the encapsulated antigen and induce tolerance by several mechanisms such as anergy induction and the activation of various subsets of Ag-specific Treg cells. Significantly, PLG NPs encapsulating gliadin are presently undergoing phase 2 clinical testing in celiac disease patients. NMO is a prime candidate autoimmune disease which may benefit from this tolerogenic therapy due to substantial evidence that the disease is primarily driven by autoimmune responses to AQP4. Therefore, we propose to test the hypothesis that tolerogenic treatment with PLG nanoparticles encapsulating AQP4 and/or its immunodominant T cell epitopes will induce specific immunotherapy of NMO via induction of anergy and AQP4-specific Tregs. Aim 1 will establish mouse models of NMO by transfer of activated T cells from AQP4 KO mice primed with either recombinant AQP4 protein (rAQP4), yielding T cells specific for multiple AQP4 epitopes, or with T cells from KO mice primed with NMO-inducing I- Ab/I-As-restricted AQP4201-220 or I-Ab-restricted AQP4135?153 epitopes to wildtype B6 or SJL recipients. As NMO patients often display autoantibodies to MOG and PLP as well as to AQP4 due, we will assess if epitope spreading leads to T cell and antibody responses to these myelin proteins in NMO mice. Aim 2 will determine the effects of tolerance induced by PLG NPs encapsulating the immunodominant AQP4201-220 and/or AQP4135- 153 T cell epitopes in rAQP4 and AQP4 peptide-induced NMO mice. Aim 3 will determine the effects of tolerance induced by PLG NPs encapsulating rAQP4 on disease initiated by transfer of rAQP4 vs. AQP4 peptide-specific T cells due to the possibility that human NMO patients recognize multiple AQP4 determinants presented by different HLA class II molecules. Tolerance induction will be assessed by clinical scoring, evaluation of demyelination and optic neuritis, and by immune criteria (T cell proliferation and cytokine production and Ab responses). It is anticipated that successful demonstration of AQP4-specific tolerance will propel the rapid clinical testing of this novel immune tolerance inducing platform for the treatment of NMO.